I'm really sorry this is the experience you are having. As I've gotten older, I've had more choice in who I spend thanksgiving with and what I eat - so hopefully you get that flexibility soon. One year I went to Mexico, which was a great way to opt out of local festivities. This year we have a couple of people with celiac attending, so we are eating nontraditional food. Also, turkey is objectively gross.
Edit: Some years I host so I can get shit faced without worrying about driving (in retrospect , I am probably "that" relative) - another great way to make the holidays tolerable.